1. Field of the Invention
This invention relates to superficially porous macroparticles composed of an impervious core coated with a number of layers of like microparticles and to a process for their manufacture. Such macroparticles are useful as column packings for chromatography, particularly liquid chromatography, as catalysts and as catalyst bases.
2. Discussion of the Prior Art
U. S. Pat. 3,505,785 discloses superficially porous macrospheroids having an average diameter in the range of 5 to 500 microns which are composed of an impervious core coated with a multiplicity of monolayers of colloidal inorganic particles having an average size in the range of 0.005 to 1.0 micron. To obtain a relatively large pore size (characteristically 1,000 A) with these particles, however, one must accept particles with surface areas that are relatively small (characteristically less than 1.0 m.sup.2 /g). The particles are extremely useful as supports for liquid-liquid (partition) chromatography but suffer, because of their small surface area, for use in liquid-solid (adsorption) chromatography.